Around 1900 radiographs were just starting to be utilized in the medical, dental, veterinary, and other health related fields. This new technology greatly aided the health practitioner in diagnosing disease and injury of the hard tissues. In more recent years, radiographs, with the aid of other diagnostic techniques, have been helpful in soft tissue diagnosis. Radiographic film (x-ray film) has gone through several evolutionary changes to improve resolution and dynamic range, reduce fogging, and increase speed (thereby requiring less x-ray exposure). Through years of clinical usage, film based radiography has become the gold standard as a diagnostic aid for health care professionals throughout the world.
In the case of medical radiology, films utilized are very large, making diagnosis and diagnostic presentation to a patient, by direct viewing, a comparatively simple task. Even in the case of dental orthodontic film, since the entire head is usually radiographed on 8″×10″ film, case presentation is not a difficult process. However, in the case of general dentistry, and most dental specialties, intra-oral dental film is used. By necessity, such films must be quite small in order to place the film inside of the patients' mouth. Further, the objects being radiographed, the patients' teeth, are small. The net result is that dental x-ray film and images thereon are exceedingly small, making diagnosis and patient case presentation utilizing these x-ray films a difficult task. After x-rays films are exposed on the patient in the dental office, then processed, the dentist must examine them in order to determine if there are ailments to be treated. Thus, the dentist may identify dental caries by noting dark (radiolucent) areas on the x-ray image. The dentist also checks the bone density and levels, examines the roots and nerves of the teeth, checks the position and development of the teeth, looks for lesions such as cysts or tumors, assesses damage when trauma occurs, and monitors periodontal conditions. All of this must be determined on a set of very small film, each of which is approximately an inch by an inch and a half round-cornered rectangle. The conventional way in which this is done is to clip the film to a dental x-ray viewer light box, (hereinafter denoted x-ray viewer) which acts as an aid in the inspection of the x-ray film. The dentist can then visually scan the entire x-ray set and render a diagnosis.
Several attempts have been made to make x-ray reading a less difficult endeavor. A variety of magnifying glass-type devices have been utilized when viewing film. This technique has been moderately successful, aiding the dentist in diagnosis. However, the patient is generally unable to view the film with the dentist, making discussion and case presentation difficult.
Another attempt to display x-ray images on a screen is a technique called direct digital imaging. This technique involves utilizing an x-ray sensing charged coupling device (CCD) that is placed in a patient's mouth then exposed to a small dose of x-rays. An image formed on the CCD device is directly sent to a computer where it is digitized. The image can then be viewed on a computer screen, and can be manipulated and printed. To date, this is an exceedingly expensive technique. Further, it is ergonomically awkward because of the fact that all x-ray images to be viewed are on a computer disk. Film sets cannot be visually scanned by the dentist. After booting up the computer, the operator must select the patient's file, and then “click” on each film to be viewed. Further, digital images do not have the image clarity and quality of film.
Another variation of this technique utilizes phosphur-covered sensors that are sensitive to x-rays. These sensors are placed in the patients' mouth, then exposed to x-rays. The sensors are then transferred to a reading device which captures the image from the sensor and sends it to a computer for digitizing. The drawbacks for this technique are the same as those of direct digital imaging.